The invention concerns a subscriber card, a subscriber unit, and an exchange for concentrating Internet frames, i.e. frames conforming to the point-to-point transmission protocol and to the Internet protocol.
Many Internet users employ the public telephone network to access their service provider. Calls conveying data between an Internet service provider and a subscriber terminal via a standard telephone network are longer than standard telephone calls. On the other hand, the data is transmitted in bursts separated by long periods of inactivity.
In an analog telephone network, a subscriber terminal sends and receives Internet frames via a modem located near the terminal and another modem located near a server constituting an access point to a data transmission network.
One particular type of modem, called an ATM/ADSL (Asynchronous Transfer Mode/Asymmetrical Digital Subscriber Loop) modem, transmits Internet frames having a high bit rate in the direction from the subscriber terminal to the network on an analog line in a frequency band above the telephone band.
In an Integrated Services Digital Network (ISDN), basic subscriber access is provided by:
two B channels each having a bit rate of 64 kbit/s, and
one D channel having a bit rate of 16 kbit/s and which is used to transmit data.
Each ISDN subscriber terminal is connected to a local exchange via a subscriber unit which can be at some distance from the exchange. Subscriber cards in the subscriber unit constitute the interface with the subscriber lines. When a subscriber uses the D channel to transmit data conventionally, the data is concentrated at the subscriber card by means of a circuit called a HDLC controller which implements the standard HDLC protocol, after which the concentrated data frames are switched in order to route them to a gateway providing access to a data frame switch.
When a subscriber uses a D channel to transmit Internet frames, those frames can be separated from frames dedicated to signaling and then routed without further processing, in the local exchange, to a node providing access to a data transmission network.
When a subscriber uses a B channel, or both B channels, to transmit Internet frames, those frames can be routed without further processing, in the local exchange, to a node providing access to a data transmission network. The access node is a remote node. It is located beyond the local exchange, or even beyond one or more transit nodes.
In an ISDN, a call to an Internet service provider occupies at least one B channel having a bit rate of 64 kbit/s but data is transmitted from the Internet service provider to the subscriber terminal at an average bit rate in the order of 5 kbit/s.
Whatever type of transmission is used between the subscriber terminal and the Internet service provider, the resources of the telephone network are therefore under-utilized. Also, Internet traffic is expanding fast. There is therefore a risk of telephone networks becoming congested by Internet traffic.
The aim of the invention is to propose a simple solution that can be implemented at low cost in existing or future exchanges.
A first aspect of the invention consists in a digital subscriber card for a telecommunication network including integrated services digital exchanges and data switches, characterized in that it includes:
first means for concentrating, on nxc3x9764 kbit/s data links, Internet frames from a plurality of digital subscriber lines before routing them to a data switch, and
second means for receiving an instruction supplied by a call processor and for controlling the first means so as to concentrate Internet frames and transmit them in a virtual circuit routing them to a data switching center when said second means receive an instruction to that effect.
The subscriber card performs a first stage of concentration of Internet frames from a digital subscriber terminal as close as possible to the digital subscriber terminal. It therefore enables the resources of the subscriber unit in which the card is located and all resources downstream of it to be used more efficiently. This solution is particularly advantageous when applied to existing digital subscriber connection cards which incorporate frame concentrator means for the D channels, since all that is then required is to modify the control means of the concentrator means. In practice, the modification often consists in modifying the software stored in an electrically re-programmable memory.
A second aspect of the invention consists in a subscriber unit for a telecommunication network including integrated services digital exchanges and data switches, characterized in that it includes at least one digital subscriber card in accordance with the invention.
The subscriber unit is a low-cost unit because all that is required is to change the subscriber cards. It performs a first stage of concentration of Internet frames from digital subscriber lines. If it includes further concentrator means, it provides a second stage of concentration of Internet frames from a plurality of digital subscriber lines.
A third aspect of the invention consists in a subscriber unit, characterized in that it includes concentrator means for concentrating Internet frames from a plurality of analog subscriber lines.
The subscriber unit provides a first stage of concentration of Internet frames from analog subscriber lines.
A fourth aspect of the invention consists in an exchange adapted to be connected to at least one subscriber unit in accordance with the invention and including call processing means, characterized in that its call processing means include means for controlling Internet frame compressor means on digital subscriber cards in accordance with the invention.
The exchange is a low-cost exchange because all that is required is to modify the call processing software of a standard ISDN exchange.
A fifth aspect of the invention consists in an exchange connected to a data transmission network and including call processing means and a switch matrix, characterized in that it further includes an Internet router and in that the call processing means include means for controlling the matrix so that calls to an Internet service provider pass through the router.
A sixth aspect of the invention consists in a subscriber unit connected to a data transmission network and including a switch matrix, characterized in that it further includes an Internet router and in that the matrix can be controlled so that calls to an Internet service provider pass through the router.
A seventh aspect of the invention consists in an exchange connected to a data transmission network and including call processing means and a switch matrix, characterized in that it further includes a plurality of modems and in that the call processing means include means for controlling the matrix so that calls to an Internet service provider pass through the modems.
An eighth aspect of the invention consists in a subscriber unit connected to a data transmission network and including a switch matrix, characterized in that it further includes a plurality of modems and in that the switch matrix can be controlled so that calls to an Internet service provider pass through the modems.
The above exchanges and subscriber units extract Internet traffic from the telephone network as close to the subscriber card as possible, to spare the resources of the telephone network.